(Rue family)

900 species in 150 genera are found in tropical and temperate regions especially in southern Africa and Australia. The family now includes genera formerly classified by some authorities in the Flindersiaceae.

This family is the source of some phototoxic chemical compounds. Phototoxicity may possibly explain some conflicting earlier reports of variable episodes of dermatitis from the woods e.g. from Fagara and Zanthoxylum.

This tree with sometimes spiny branches is cultivated throughout
India (mainly in temple gardens, because of its status as a sacred tree) and in other subtropical regions. A clear, gummy sap, resembling gum arabic, exudes from wounded branches and hangs down in long strands, becoming gradually solid. It is sweet at first taste and then irritating to the throat (Burkill 1935, Morton 1987). The plant yields 8-methoxypsoralen (Pathak et al. 1962).

Amyris balsamifera L.

(syns Amyris funckiana Turcz., Elemifera balsamifera Kuntze)

West Indian Sandalwood

West Indian Sandalwood Oil is derived from this species. East Indian Sandalwood Oil is derived from Santalum. Hausen (1970) cites Gougerot and Delzant (1940) for contact sensitivity to the oil.

Amyris spp. used to be considered one or the main sources of rosewood (Holtzapffel and Royle 1843, Burn — undated) but now provide very little timber (Record and Hess 1943). Amyris Oil, known as West Indian Sandalwood Oil, was formerly extracted from the wood of Amyris simplicifolia. Großmann (1920) stated that working with Amyris and some other rosewoods (Aniba but improbably Convolvulus) caused headache, weakness, drowsiness, dyspnoea and sometimes dermatitis.

This tree, which is known in horticulture, yields 5-methoxypsoralen (Dean 1963).

Chloroxylon swietenia DC.

(syn. Swietenia chloroxylon Roxb.)

Satinwood, East Indian Satinwood

The genus Chloroxylon DC. was until recently classified in the family Flindersiaceae.

The timber is very lasting and is largely used in veneering. The tree also yields a gum. Two outbreaks of dermatitis occurred in cabinet-makers working with East Indian satinwood in Glasgow ship-building yards; not all the men exposed were affected. The latent period became shorter in successive attacks (Jones 1904). Gardiner (1908) described a further case in a cabinet maker and noted that a mixture of putty and linseed oil (see Linum usitatissimum L., fam. Linaceae) rubbed on the lesions seemed to cure a sufferer. Neither of these authors was able to identify unequivocally the botanical source of the wood to which their patients had been exposed. Legge (1907) wrote: "there can be no doubt that East Indian satinwood possesses much more irritant properties than the West Indian variety". Bidie (1905) had earlier proposed exactly the opposite view entirely on the basis of his suppositions. West Indian satinwood is a name for Fagara flava. Another outbreak involving 25 cabinet makers was reported from Germany; the offending timber was identified only as "satin-wood" (Anon 1909). According to Woods & Calnan (1976) both types of satinwood had been imported into England since about 1780; they cite Sheraton (1803). Genuine satinwoods were increasingly replaced by substitutes. The identity of the wood is therefore uncertain.

Auld (1909) investigated the wood of Chloroxylon swietenia and found, among other substances, an alkaloid chloroxylonine. The skin effects of this compound were investigated by Cash (1911) on his own person and on volunteers. He observed what has since come to be known as allergic sensitisation by a spontaneous flare phenomenon (active sensitisation by patch testing); 0.0000165 g of the compound produces positive patch test reactions. He distinguished the wood of Chloroxylon swietenia from West Indian satinwood (Fagara flava); the latter was not allergenic but slightly irritant by patch test. Hausen (1970) suggests that substitutions for satinwoods may have produced fluctuations in toxicity and that photosensitisation by chemical compounds of Fagara flava may have played a role. According to Woods & Calnan (1976) Chloroxylon swietenia also contains photosensitisers. They cite the finding of xanthyletin in the plant by King et al. (1954). Wilkinson (1971, personal communication) cited by Woods & Calnan (1976) has seen a case of clinical photosensitivity to Chloroxylon swietenia but the findings could not be confirmed experimentally. According to McCord (1958) exposure to the wood can cause gastrointestinal disturbances and headache.

Citrus

12 species are native to southern China, south-east Asia and Indo-Malaysia. A nomenclature of the cultivated species is provided by Usher (1974):

Fruit canners are subject to paronychia and loss of nails (Kingery and Thienes 1925, White 1941). 10% of cases of dermatitis of the eyelids were attributed to contact sensitivity to fruit peel (Hazen 1944). Atopic allergy of the hands from transepidermal penetration of agents of fruits and also by ingestion of fruits was postulated by Rowe (1946). The subject of contact urticaria was discussed by Maibach and Johnson (1975).

Mycotic infection of fruit canners known as "fruit poisoning" was treated by application of thymol, oil of cinnamon (Cassia) and oil of clove (Syzygium) (Myers and Thienes 1925). Paronychia of orange-workers was attributed to a fungus of the family Mucoraceae (Sutherland-Campbell 1929).

d-Limonene is found in orange oil and in many other essential oils. Sensitisation by limonene is probably attributable to autoxidation products (Opdyke 1974).

According to Woods and Calnan (1976), citronnier used to be popular with French cabinet-makers (Hinckley 1960) but in Germany the name Zitronenholz has been much more widely applied. According to these authors, it seems to have referred mainly to satinwoods, such as Fagara flava and Chloroxylon swietenia with a lemon scent (Gayer 1928) which were probably responsible for most if not all the reported cases of Zitronenholz dermatitis.

Citrus aurantiifolia Swingle

(syn. Citrus medicavaracida)

Lime, Mexican Lime, West Indian Lime

This species forms a small tree armed with stiff sharp spines capable of causing mechanical injury.

Citrus aurantifolia [sic] has been reported to evoke photodermatitis (Pathak et al. 1962, Van Dijk & Berrens 1964). The oil of the fruit peel was observed to be photosensitising. Oils from different kinds of lime varied in their activity (Sams 1941). The furanocoumarins of the species are given by Pathak et al. (1962); C. acida yields 5-methoxypsoralen. The role of photoallergy versus phototoxicity requires clarification (Sams 1956).

Citrus aurantium L.

Bigarade, Seville, Orange, Sour Orange

Early reports of dermatitis from oranges were reviewed by Touton (1932), Prosser White (1934) and Schwartz (1938).

Orange pickers suffer pricks and scratches from the thorns of the plant and secondary infection (Pardo-Castello 1962).

In growing oranges, dermatitis from insecticides and fertilisers can occur: in packing, splinters from boxes, dermatitis from washing solutions and from citrus oils: in canning, dermatitis and paronychia due to citrus oils and juices (Schwartz 1938). There are two reports of dermatitis attributed to sensitivity to dyes used for dyeing the skins of Florida oranges (Schwartz 1938, Traub 1936, Baer et al. 1948).

A man who had contact dermatitis from dyed socks was contact-sensitive to Citrus Red No. 2 (also known as CI Solvent Red 80) used for dyeing the skins of oranges (Mitchell 1972).

Carnauba wax (from Copernicia prunifera H.E.Moore, fam. Palmae) and paraffin wax are used for waxing the skins of oranges. Contact sensitivity attributed to carnauba has been reported (Greenberg and Lester 1954).

Cheilitis and stomatitis were reported from eating oranges (Zakon et al. 1947). Persons who suck citrus fruits can develop circumoral dermatitis and hyperpigmentation, and cheilitis (Behl et al. 1966). Cheilitis was attributed to the volatile oil of oranges (Sutton and Sutton 1953). Dermatitis of the hands from oranges was reported by Michel (1953).

Hjorth (1971) described a man with severe hand eczema for 10 years who, because he reacted to balsam of Peru on patch testing, was told to avoid orange peel. To test the validity of this advice, the patient ate a jar of orange marmalade and in 12 hours had his worst attack of hand eczema. He then avoided "perfumes, cola drinks, vermouth, throat tablets, cinnamon and other items" and his hand eczema cleared.

Sensitisation to limonene has been considered responsible for dermatitis from oranges but some cases of contact sensitivity to orange peel show no sensitivity to lemon peel which also contains limonene (Bonnevie 1939).

Oil of Orange derived from orange peel has been reported to produce dermatitis (Greenberg and Lester 1954). Oil of Orange Flowers (Oil of Neroli) derived from orange flowers has been reported to produce dermatitis and photosensitivity (Greenberg and Lester 1954). Oil of Petitgrain distilled from the leaves has been reported to cause contact dermatitis and photosensitivity (Greenberg and Lester 1954). Contact sensitivity to Orange sweet terpeneless was reported by Larsen (1975).

Patch testing with oranges and lemons:

Schwartz (1938a,b) reviewed the literature concerning dermatitis from citrus fruits and some chemical information on the oils of the rinds. The oil in the peel of citrus fruit is contained in the few layers of oil cells on the surface of the peel. Citrus oils are exceedingly irritating to the skin and will produce positive reactions when used in patch tests on normal skin in less than an hour. Limonene and citral are also irritant by patch test. The juice of the fruit is generally not irritant by patch test. Lemon juice is said to be more irritant than orange or grapefruit juice because of its greater content of citric acid. Lemon peel may appear more often irritant than orange peel because lemons are seldom waxed. It is necessary to read these reports before attributing allergic contact dermatitis to citrus fruits and some reports of patch testing as indicating sensitivity must be discarded. However, it is considered that such sensitivity can occur in industry and that dermatitis could result from the use of oils of orange and lemon and limonene in perfumery.

Statements that the white under-surface of the peel (the mesocarp) is allergenic and that the outer surface of the peel (the exocarp) produced no reaction must be accepted with caution. It is possible to patch test with the mesocarp contaminated with citrus oil and to obtain a positive reaction; and to patch test with the exocarp which is unbroken and therefore with intact oil cells and to obtain a negative reaction. These apparently paradoxical results depend on the materials used and the technique used for obtaining samples of the fruit.

There is a great difference in patch testing with citrus fruit gathered directly from the tree and with citrus fruit obtained from stores. Before the citrus fruit finally reaches the consumer, it receives various treatments, among which is a wax finish on the surface of the peel. Patch testing with waxed citrus peel will not allow the actual peel to touch the skin, or if it does touch the skin, it will do so imperfectly. The thickness of the coat of wax on the peel will determine whether the peel will come in contact with the skin. When the peel is removed from the fruit for the purpose of patch testing, the wax coating may or may not have been cracked; the oil in the oil cells of the peel may or may not touch the skin, depending on whether the peel itself has been cracked. The number of days that the orange has been kept in storage will have some bearing on how dry the peel is and how much oil there is left in it. All these things have a marked bearing on the results of patch tests and may account for many of the negative results obtained by authors from testing with orange and grapefruit peel.

"I believe, from the experiments which I made, that oil of lemon, oil of orange and oil of grapefruit will irritate by far the larger proportions of skins if allowed to remain on in the form of a patch test" (Schwartz 1938, in discussion of Beerman et al. 1938).

Summary of the above reports leads to the conclusion that patch testing with citrus fruit rind (peel) named exocarp, applied as is, does not produce reliable or meaningful information concerning sensitivity.

A suitable patch test concentration of orange peel is perhaps 10% or 25% w/w in petrolatum.

Oil of petitgrain derived from this species can produce irritation and photosensitisation (Greenberg and Lester 1954, Klarmann 1958).

According to Furia & Bellanca (1971), oil of petitgrain is derived from Citrus aurantiumsspamara.

Murray (1921) recorded a case of occupational dermatitis of the fingers, hands and forearms in a 25 year old female who was "exposed to the juice" of the bitter orange. The nature of work not described; nor was the plant material identified by a botanical name.

Citrus aurantiumvarbergamia

(syn. Citrus bergamia)

Bergamot Orange

Oil of bergamot can produce photodermatitis. The fruit yields furanocoumarins, including 5-methoxypsoralen (Pathak et al. 1962). The name bergamot dates from 1696 from the town of Bergamo in Italy.

Freund (1916) described a skin disease in necklace or berlock-form in four patients who applied eau de Cologne to their skin, directly after which they exposed themselves to sunshine. Dermatitis was followed by hyperpigmentation. He suspected that oil of bergamot was responsible.

In modern German, Berlocke is the word for a pendant (a kind of necklace). The French equivalent is berloque. In present-day dermatologic literature one sees berloque and berlock which are reasonable and berlocque and Berloque (suggesting an eponym by its initial capital) which are incorrect (Harber et al. 1964).

Eau de Cologne, containing Oil of Bergamot, is the commonest cause of berloque pigmentation which may or may not be accompanied by visible dermatitis (Espersen 1952). He reviewed the literature and noted that Kuske (1940) had found more than 100 publications on the subject. Goodman (1931), Klaber (1942), Greenberg and Lester (1954) and Pathak (1974) also reviewed the subject.

Erythema and vesicles appear at the skin site of contact following exposure to sunlight; the reaction is often present on the neck, hence the pendant-like distribution (Gross and Robinson 1930, Rogin and Sheard 1935, Lane and Strauss 1930, Downing 1932, Klarman 1958). The dermatitis is more severe in natural blondes but the residual pigmentation is more severe in brunettes. Only some persons are susceptible to photosensitisation by Oil of Bergamot and these only at certain times and/or certain sites (Harber et al. 1964). They discuss four hypotheses and it seems possible that photoallergy is involved as well as phototoxicity from furanocoumarins. Bergamot oil produced positive patch test reactions in 3/590 (0.5%) of patients tested (Menighini et al. 1971).

In 1916 Freund reported a number of patients, observed some years earlier, who had a peculiar pigmentation of the skin of the neck, which was supposedly due to the application of toilet-water to the exposed parts followed immediately by sunlight. Freund made a number of experiments, and was convinced that oil of bergamot was the ingredient responsible.

Eight years later, Rosenthal, unaware of the work of Freund, reported a patient before the Berlin Dermatological Society (Rosenthal 1925) with a skin-eruption that he named "Berlock dermatitis". The description given by Rosenthal is an excellent one, for it serves for other reported cases, and explains some of the other names listed for the affliction. Rosenthal's description, as given by Lane and Strauss (1930), is as follows:

"Two or three dark yellowish brown streaks of pigmentation are seen running down from the front or the back of the neck. Their upper portions are hardly visible and are poorly outlined, but farther down, and especially at the lower margin, they become more evident and darker. The streaks may also appear on the face, on the arms and on the trunk. The shape, outline and the increase of pigment towards the lowest part of the streaks is especially characteristic. They give the appearance of being caused by a dark-colored fluid running down. In the region of the pigmentation, by the use of a magnifying glass, distinct signs of inflammation are seen; also dilatation of the capillaries and prominence of the openings of the hair follicles. This is a dermatitis which I called berlock dermatitis because the streaks of pigment remind me of the pendants of a necklace or watch chain."

The true nature of the disease was not recognized at the Berlin meeting and many guesses were made. A month after Rosenthal's presentation, Fischer (1925) presented two similar cases, and although no diagnosis was made, the possibility of external irritation was suggested.

In 1925 Hoffmann and Schmidtz rediscovered the cause of the condition and unearthed the work of Freund. In 1926 reports were published by Galewsky, Stein, and Falkenstein. In 1927 Samek, Linser, Freund and Brito Foresti reported cases. In 1928, Pozzo, Langer, Zurhelle, Urbach and others reported cases.

Gross and Robinson (1930), Lane and Strauss (1930) and Goodman (1931) reported cases from the United States.

Axmann, in 1925, claimed that he produced pigmentation on spots of depigmented skin (vitiligo) after rubbing eau de Cologne on the areas. Du Bois, in 1927, found no increase of pigmentation following the application of pure alcohol, and thought that the eruption was due to essential oils and sensitisation to light. Uhlmann, in 1927, exposed areas of depigmented skin to the beam from a quartz mercury vapour lamp, protecting the normal skin, and found no increase in pigmentation, although the vitiligo areas became red. The experiment was repeated, but he applied eau de Cologne to the depigmented spots before radiation with the mercury vapour arc. He was enabled by this means to produce pigmentation in the previously pigment-free areas. Uhlmann reported that the oil of bergamot alone did not produce the colour change, but that it required oil of bergamot in alcohol.

Freund, also in 1927, applied eau de Cologne to a boy's forearm and exposed the surface to sun and sea-water. The boy developed an inflammation on the site followed by pigmentation. Freund then used the oil of bergamot followed by sun exposure, and produced a blister which was followed by pigmentation. The attempt to pigment unpigmented areas of vitiligo was not successful.

Zurhelle, in 1928, reported that he considered perspiration to be one of the factors in the production of the dermatitis. He stated that the inflammatory process was strongest in blondes, but that the tendency for the formation of pigment was stronger in brunettes. Szántó in 1928 used oil of bergamot in alcohol on depigmented skin and claimed eighteen successes in twenty-two trials. Bonnet, in 1928, reported negative results for production of pigment in depigmented areas skin by this method. Phipps, in 1929, reported the return of pigment in a case of vitiligo after the use of oil of bergamot and ultra violet radiation. Gross, reporting in 1930, had one success and several failures.

Citrus hystrix

The wood is said to be injurious to wood-workers (Vonkennel 1929).

Citrusxlimon Burm.f.

(syn. Citrus medicavarlimon L.)

Lemon, Zitrone, Citronnier

Lemons have been reported to cause dermatitis (Fanburg and Kaufman 1931, Puglisi 1951). Lemon peel is frequently irritant by patch test. Lemon juice appears to be more irritant than orange juice since it has a higher content of citric acid. Lemon peel is irritant by patch test (Beerman et al. 1938).

Keil (1947) observed a patient with contact dermatitis from Oil of Lemon: the patient was also contact sensitive to Oil of Citronella (Ceylon), Oil of Citronella (Java) (Cymbopogon) and to turpentine (Pinaceae). Further patch tests demonstrated contact sensitivity to dipentene (limonene), α-pinene and β-pinene. The principal allergen appeared to be limonene present in these materials.

Lemon and lime (Citrus aurantiifolia Swingle) pickers at times are seen with bands or lines of brown or black skin pigmentations caused by the oil from the skin of these fruits (Pardo-Castello 1962). Patch-testing to lemon is noted under Citrus aurantium.

Lemon juice or lemon peel applied to the face to make the skin smooth caused dermatitis of the face in four women. Patch tests were not recorded (Minami 1968).

Citrusxlimonia Osbeck

(syn. Citrus limonum Risso)

Canton Lemon, Lemandarin, Mandarin Lime, Marmalade Lime, Rangpur Lime

Citrus limonum yields 5-methoxypsoralen (Pathak et al. 1962).

Citrus medica L.

(syn. Aurantium medicum M.Gómez)

Citron

Cedro, Cedrino, and Cedrone are varieties of citron (McNair 1926). Oil of Lemon (Oil of Cedro) has been reported to cause dermatitis (Greenberg and Lester 1954, Klarmann 1958).

Citrus mitis Blanco

Perry & Metzger (1980) record that the pain of nettle stings inflicted by Dendrocnide Miq. species (fam. Urticaceae) may be relieved by swabbing the affected parts with the juice of Citrus mitis. No detail is provided as to which part of this plant is used.

Citrus paradisi

Grapefruit

Men who wore few clothes tore the fruit open and the juice spattered on their skin; hyperpigmentation of the skin of the abdomen resulted (Simons 1952). Oil of grapefruit did not have any photosensitising activity (Sams 1941).

Clausena engleri Tanaka

(syns Clausena platyphylla Merr., Clausena yunnanensis C.C.Huang)

The glands of Clausena platyphylla have a caustic secretion (von Reis Altschul 1973).

Cneorum tricoccon L.

Spurge Olive, Little Olive Tree, Olivilla

According to Lewis & Elvin-Lewis (1977), the whole plant is considered to be powerfully rubefacient. However, the possibility of mistaken identity cannot be excluded: the common name "spurge olive" is also used for Daphne mezereum L. and for Daphne oleoides Schreb. (fam. Thymelaeaceae). Indeed, the common name used for Cneorum tricoccon in Italy — timelea tricocca — also alludes to the morphological similarity between these botanically unrelated genera. Skin irritancy is a well-researched feature of the Thymelaeaceae.

The genus Cneorum L. was formerly classified in the Simaroubaceae, and more recently in its own family, the Cneoraceae.

Dictamnus spp.

Creosote Bush

A worker developed dermatitis after two weeks exposure to the wood dust which he was cooking and evaporating to prepare nordihydroguaiaretic acid (NDGA) used as an antioxidant for lard (Weber 1953). This chemical which occurs in the resinous exudates of many plants is commonly derived from Larrea.

A worker in a pharmaceutical factory, and a pharmacist, developed dermatitis of the face and hands from handling Vitamin AD tablets and lanoline cream respectively. Patch tests to NDGA, contained in these preparations, was positive 2% in vaseline. In the pharmaceutical worker, a patch test to hydrogenated Oil of Soybean (Glycine) containing 0.15 per cent NDGA was positive. The compound was not irritant at a concentration of 5% in vaseline. Many of the fats and oils used for local therapy contain stabilisers but the contents of these are not indicated (Jorgenson and Hjorth 1970).

Dictamnus albus

(syn. Dictamnus fraxinella)

Dittany, Candle-Plant, Gas Plant, Burning Bush

The plant is cultivated as an ornamental shrub or hedge. Volatile and inflammable oil is excreted, so that on hot calm days the air around the plant may sometimes be ignited, hence the colloquial name burning bush.

The human skin is more susceptible if wetted. The seed pod is the most injurious part of the plant, next the leaves. Somner and Jillson (1967) clearly defined the role of sunlight in evoking photodermatitis from the plant and they tabulated the clinical features which enable a distinction from poison-ivy (Toxicodendron) dermatitis to be made. The plant is a source of psoralens (Evans & Schmidt 1980).

Dictamnus albusvarcaucasicus

(syn. Dictamus fraxinella)

Linear bullous dermatitis followed by hyperpigmentation resulted from contact with the fresh plant; old dried plant was inactive (Gorodinsky 1938).

Dictamnus dasycarpus

Bullous dermatitis from contact with this species was most commonly observed at the time of its blossoming when 3-5% of all dermatological out-patients were affected (Stekhun and Kurnakov 1962).

Esenbeckia

38 species are found in tropical America and the West Indies. The bark of some Brazilian species is used like angostura (Galipea) as a bitter for gin.

Esenbeckia leiocarpa

Guaranta

See Euxylophora.

Euxylophora

One species is found in the Amazon region and in Brazil.

Euxylophora paraensis

Amarelo, Pau Setim, Boxwood

Esenbeckia leiocarpa

Guarantá

Raputia magnifica

Arapoca

Raputia alba

Arapoca Branca

Balfourodendron riedelianum

Guatambú

Freise (1936) described fifteen cases of dermatitis caused by these satinwood or boxwood substitutes, and two similar cases from Fagara flava. Most of the eruptions were mild and confined to the finger-webs and other exposed areas, as the sawdust of fresh wood is coarse and does not penetrate under the clothes. Some were more severe, however, with widespread oedema accompanied by general symptoms, usually going on to vesicular dermatitis and often gangrenous ulcers which in three cases proved fatal. Freise confirmed the irritant action of the sawdust on his own skin and on laboratory animals.

The berry is acrid and tastes strongly of lemon (Citrusxlimon Burm.f.) leaving a persistent burning sensation in the mouth (Watt & Breyer-Brandwijk 1962).

Fagara caribea

According to Woods and Calnan (1976) this species is one of a number of woods called zebrawood and not the only one likely to cause dermatitis. They index woods named zebrawood as Astronium, Fagara caribaea and (possibly incorrectly) Baphia and as African zebrawood, Microberlinia.

Fagara davyi Verdoorn

Knobwood, Knobby Tree, Fever Tree

The vernacular name for this tree in Afrikaans is perdepram, literally "horse's teats", which refers to the terrific 3-inch knobs that stud the trunk; these are usually tipped with sharp thorns (Menninger 1967).

Fagara heitzii

Olon

The wood is said to be capable of producing dermatitis (Hausen 1970, Orsler 1973).

Fagara leprieurii

(syn. Fagara angolensis)

The pulverised bark is used as a counter-irritant (Irvine 1961).

Fagara macrophylla

Olon

This species can cause dermatitis and upper respiratory symptoms in wood-workers (Rochaix and Vieux 1936, Zafiropoulo et al. 1968). The bark makes part of a mixture, with Diospyros xanthochlamys and Mansonia altissima which is used for irritant and blistering purposes (Irvine 1961).

Dermatitis and coryza affected all eight men present when a dried tree trunk of olon was sawn up producing much fine dust. A wetter section of the same trunk was sawn elsewhere without any trouble (Pillon and Martinez 1935). Rochaix and Vieux (1936) tried experimentally to sensitise rabbits with olon sawdust but could demonstrate only a primary irritant effect. Orsler (1973) and Hausen (1970) received trade reports of irritation by olon wood. Freise (1936) found xanthotoxin and an alkaloid in the wood. More recently, suberosin and the coumarins, psoralen and xanthotoxin have been found in Fagara spp. (King et al. 1954). Earlier workers reported pungent resins from the wood (Auld and Pickles 1912).

Flindersia australis R.Br.

Moah, Crow's Ash, Australian Teak, Nutwood

Australian moah wood, reported by Pflanz (1908) to produce dermatitis of the face, hands and arms in wood-workers, has been considered by some authors to be a species of Madhuca Buch.-Ham. ex J.Gmelin (fam. Sapotaceae). However, according to Woods & Calnan (1976) Flindersia was also named Australian moah tree at that time. Pflanz (1908) could not reproduce the eruption that occurred in his wood-worker patients with the sawdust or extracts of the wood, either on the patient or himself. Matthes & Schreiber (1914) found that none of the several constituents they isolated from Flindersia australis wood irritated the skin. Early reports of dermatitis from the wood were reviewed by Hausen (1973). According to Cleland (1943), mill-hands noted reactions to the wood.

Flindersia brayleyana F.Muell.

(syn. Flindersia chatawaiana Bailey)

Queensland Maple, Silkwood Maple

A cabinet-maker developed dermatitis of the hands, forearms, neck and face after working with this wood for over 20 years. Respiratory symptoms occurred in other workers (MacPherson 1925). A factory worker developed a severe skin eruption from handling the wood (Cleland 1943).

A factory worker developed a severe skin eruption from handling the wood (Cleland 1943).

Glycosmis pentaphylla

This species yields furanocoumarins (Pathak et al. 1962).

Halfordia scleroxyla

Ghittoe, Saffron Heart, Kerosene Wood

The wood is very inflammable even in a green state, hence the name kerosene tree. Splinters of the wood, when they penetrate the skin, cause festering. When chewed, or used to clean the teeth, as is the habit sometimes of men working in saw-mills, the splinters cause trouble with the gums (Webb 1948a).

Haplophyllum tuberculatum

Possibly this species has been reported to cause facial dermatitis and oedema in the Sudan (Chalmers and Pekkloa cited by Simons 1953).

The root is used as a topical application for bubonic plague, apparently for a rubefacient effect (Watt & Breyer-Brandwijk 1962).

Limonia acidissima

Elephant Apple, Wood Apple

The wood is useful and yields a gum. The edible fruit is used in Japan as a substitute for soap.

Luvunga scandens

This evergreen plant is sometimes grown for ornamental purposes in the citrus belt; the fruit has a lemon-like rind. The plant is potentially phototoxic from a yield of 8-methoxypsoralen (Pathak et al. 1962).

Melicope erythrocca

Tingle-Tongue

The plant is irritant to the tongue (Everist 1972).

Orixa japonica

This tree causes dermatitis among agricultural workers (Ishibashi 1937). It is used as a fertiliser in Japan and is a type of stink tree or stink wood. Ocotea (Lauraceae), Zieria (Rutaceae), Foetidia (Foetidiaceae) and Nyssa (Nyssaceae) are also called stink woods (Schwartz et al. 1957).

Pelea anisata

Mokihana

The fresh plant when applied in the form of a lei (neck-garland) to the bare, perspiring neck for half an hour, can make the wearer very uncomfortable for a week or so afterward (Arnold 1968).

Phebalium argenteum Sm.

Western Australian Blister Plant

The plant is a small shrub about 1m high with white flowers and silvery scurfy leaves which grows in south-western Australia, and has been adapted to cultivation in California. Yellow flowers also occur. The plant blisters the human skin if handled (Morrison 1899, Maiden 1909b). Cleland (1914b) rubbed the dew-laden leaf on the back of his hand. No irritation was noted immediately. Erythema was first observed at 24 hours and within 48 hours bulla formation occurred at the site. Hyperpigmentation surrounding an area of leucoderma persisted for about 5 years. On several other occasions, he tried to produce similar results, apparently with the same plant, but failed. Francis and Southcott (1967) do not mention a role of sunlight for evoking reactions but since the plant yields psoralen (Finlayson 1928, Bose and Finlayson 1938) phytophotodermatitis seems to be possible for contact with the plant.

Pilocarpus jaborandi

Pernambuco Jacorandi

This and other Pilocarpus species yield the alkaloid pilocarpine which can cause allergic keratoconjunctivitis (Duke-Elder 1965). High concentrations of pilocarpine in hair preparations can produce irritant effects (Greenberg and Lester 1954).

Pilocarpus pennatifolius

Jaborandi

The leaves form official Folia Jaborandi. Prolonged contact with the powder can cause irritation of the skin (Dispensatory 1884).

Poncirus trifoliata Raf.

(syns Aegle sepiaria DC., Citrus trifoliata L.)

Japanese Bitter Orange, Hardy Orange, Trifoliate Orange

The branches bear stout green spines, which have led to the use of this shrub for hedging purposes (Hunt 1968/70).

The taxonomy of the genus is confused (Bailey and Bailey 1941) and phytochemical differences are known in sub-species and varieties (Szendrei et al. 1973). Ptelea isophylla and P. trifoliata are known in horticulture as ornamental shrubs.

Ptelea angustifolia

(syn. Ptelea lutescens)

Hop Tree

This species grown as an ornamental shrub in New York State was observed to evoke photodermatitis (Muenscher and Brown 1944).

Ptelea aptera

(syn. Taravalia)

This species yields psoralen (Dreyer 1969).

Ptelea baldwinii

(syn. Ptelea angustifolia)

Wafer Ash, Hop Tree

Contact reactions to this plant have been reported (Muenscher and Brown 1944).

Ptelea crenulata

This species yields psoralen and bergapten (Dreyer 1969).

Ptelea trifoliata

Positive photopatch test reactions to an alcoholic solution of the leaves of this shrub could not be confirmed on retesting with the stored solution (Lynne-Davies G and Mitchell JC 1973 — unpublished observation).

The vapour of rue raises up blisters, wheals and other accidents on the face (Gerarde 1636).

Rue oil had phototoxic activity but was not found to be sensitising (Opdyke 1975).

Ruta chalepensis

This species yields 8-methoxypsoralen (Pathak et al. 1962).

Ruta graveolens L.

Common Rue

The plant was known by the Ancients to produce a pustular eruption of the hands in those who gathered it (Dispensatory 1884). The plant is irritant and vesicant (Bigelow 1817, Oesterlen 1856, Piffard 1881). Handling of the flowers and fruit produced erythema, burning, itching and vesication (Van Hasselt 1862). While the fresh leaves have vesicant effects, much of this activity is dissipated by drying (Loudon 1855). Bazin (cited by White 1887) reported the case of a druggist who developed itching, grouped vesicles then large bullae on the hands after gathering rue. On a second occasion, he was careful to take the branch only between the finger and thumb and to cut it below with scissors; however, an eruption developed, still more intense, and covered the whole surface of the right hand. Photodermatitis from the plant with positive photopatch tests was reported by Garat et al. (1948) and Muenscher and Brown (1944). Klauder and Kimmich (1956) refer to dermatitis from the plant.

Seven or eight species are native to the Himalayas, eastern Asia and the Philippine Islands. The plants are dioecious. An oil from the leaves of S. laurifolia is used for scenting soap (Usher 1974). Several species are known in horticulture.

Dermatitis from Fagara spp., mainly Fagara flava, was well known among labourers in the West Indies (Grabham 1905). This author reported that he himself had had such dermatitis. A joiner who worked with Fagara flava developed dermatitis; a patch test to the sawdust or this wood alone produced a positive reaction (Wechselmann 1909). This author stated that he found chloroxylonine (the sensitising alkaloid of Chloroxylon swietenia) in Fagara flava an obtained positive patch test reactions with it on his patient and himself, but not on two volunteers. The colloquial names of Zanthoxylum flavum (syn. Fagara flava) include West Indian satinwood, Jamaica or San Domingo satinwood, espenille, yellow sanders, atlaswood, citronwood and zitronenholz.

Many of the colloquial and trade names are used for other woods. Several other species of Zanthoxylum and related New World genera furnish satinwoods of poorer quality and some of these have been reported to produce ill effects (Philip Smith 1920b, Lewin 1928). Freise (1936) described fifteen cases of dermatitis caused by satinwood or boxwood substitutes (Euxylophora paraensis, Esenbeckia leiocarpa, Raputia magnifica, R. alba, Balfourodendron riedelianum) and two similar cases from Zanthoxylum flavum (syn. Fagara flava). The dermatitis was usually mild and confined to the fingerwebs and other exposed areas. He noted that the sawdust of fresh wood was usually coarse; it did not penetrate under the clothing. Some cases had more severe dermatitis, with widespread swelling and constitutional symptoms, usually proceeding to vesicular dermatitis and often gangrenous ulcers which in three cases proved fatal. He confirmed the irritant action of the sawdust on his own skin and on laboratory animals. The species Esenbeckia leiocarpa and Euxylophora paraensis contain the phototoxic compound, xanthotoxin (Hausen 1970).

Satinwood was found to cause dermatitis by Siegheim (1909) and Volk (1911) but the botanical species responsible were uncertain and the patch test results equivocal.

The reports of dermatitis from satinwoods by Oppenheim (1909), Brezina (1913), Noll (1931) named as satinwood, atlaswood, citronwood or zitronenholz may have referred to Zanthoxylum flavum (Fagara flava) or to some other species.

This species is potentially phototoxic from a content of 8-methoxypsoralen (Pathak et al. 1962).

Zanthoxylum fraxineum

Prickly Ash, Toothache Tree

The bark is used in America as a toothache remedy.

Zanthoxylum hirtellum

The bark is prickly. The bark is pounded to knock off the prickles and put into a hollow tooth as a counter-irritant (Burkill 1935).

Zanthoxylum myricanthum

Thorny Ivy-Rue

The common name is derived from a resemblance to ivy (Hedera helix, fam. Araliaceae) and rue (Ruta graveolens). The species name indicates "thousands of thorns".

Zanthoxylum piperitum

Japanese Pepper

The fruit is used as a condiment. The plant is chewed and the resulting saliva is applied to the face: the skin of the face is then said to be unaffected by "varnish poisoning" (Rhus vernicifera, fam. Anacardiaceae) (Smith 1969).

Zanthoxylum veneficum

Thorny Yellow-Wood

The bark possesses a peculiar tingling hot taste like aconite (Aconitum napellus, fam. Ranunculaceae) (Webb 1948a). The plant derives its specific name from its poisonous property.

Gerarde J (1636) The Herball or Generall Historie of Plantes. Very much enlarged and amended by Thomas Johnson citizen and apothecarye of London, 2nd edn. London: A Islip, J Norton and R Whitakers [WorldCat][url][url-2]

Holtzapffel, C. and Royle (1843) Descriptive catalogue of the woods commonly employed in this country for the mechanical and ornamental arts. An extract from: Turning and Mechanical Manipulation. London, Holtzapffel, cited by Woods and Calnan (1976).

Zaynoun, S.T., Johnson, B.E. and Frain-Bell, W. (1977) A study of oil of bergamot and its importance as a phototoxic agent. I. Characterization and quantitation of the photoactive component. Brit. J. Derm. 96: 475.

Zaynoun, S.T., Johnson, B.E. and Frain-Bell, W. (1977) A study of oil of bergamot and its importance as a photoxic agent. II. Factors which affect the phototoxic reaction induced by bergamot oil and psoralen derivatives. Contact Dermatitis 3: 225.